‘PUSH-PULL’
TECHNOLOGY: ‘Push-pull’ is a novel approach in pest
management which uses a repellent intercrop and an attractive
trap plant. Insect pests are repelled from the food
crop and are simultaneously attracted to a trap crop.
A ‘push-pull’ strategy was developed by ICIPE and its
collaborators for the control of stemborers and striga
weed in resource-poor maize farming systems. This technology
controls both stemborers and striga and improves soil
fertility. Maize is intercropped with a legume, silverleaf
desmodium (Desmodium uncinatum) and Napier grass (Pennisetum
purpureum) is planted around the intercrop (diagram
above). The desmodium produces volatile chemicals, such
as (E)-ß-ocimene and (E)-4,8-dimethyl-1,3,7-nonatriene,
which repel the stemborer moths from the maize ('push')
while those released by Napier grass, such as octanal,
nonanal, naphthalene, 4-allylanisole, eugenol and linalool,
attract female moths ('pull') to lay eggs. Desmodium
roots produce chemicals which stimulate Striga seed
germination, such as 4'',5''-dihydro-5,2',4'-trihydroxy-5''-isopropenylfurano-(2'',3'';7,6)-isoflavanone,
and others which inhibit their attachment to maize roots,
such as 4'',5''-dihydro-2'-methoxy-5,4'-dihydroxy-5''-isopropenylfurano-(2'',3'';7,6)-isoflavanone
(suicidal germination), thereby reducing Striga seed
bank. The legume also improves soil fertility through
nitrogen fixation.

Both
plants provide quality fodder for livestock. Therefore,
farmers using ‘push–pull’ technology for pest control
not only reap three harvests (maize, Napier grass and
desmodium); they also dramatically reduce the devastating
effects of the parasitic weed Striga hermonthica through
the effects of desmodium.